Labyrinth question~Please Help!

I have a question.....if you can help, please do! On several websites I have read that in the movie Labyrinth that Sarah's real mother was named Linda. If this is true, WHERE in the movie does it reveal this....I have watched it over and over and I still see nothing. (Maybe it's written on something in her room....I dunno!) Maybe I'm losing it!!

Perhaps this is a bit of info that was included in the novelization of the film. It could also be written in the script and perhaps might have even originally been an actual piece of dialogue that was either cut or changed.

Whatever the case, I'm assuming whatever sites have cited this info have done so because it was documented officially somewhere.